Radio telegraph keying system



Sept. 4, 1928.

L. C. YOUNG RADIO TELEGRAPH KEYING SYSTEM Filed Dec. 15. 1926 .r=- LINVENTOR.- [e 0 67%4159 BY ATTORNEY Patented Sept. 4, 1928.

UNITED STATES I 1,683,118 PATENT OFFICE.

LEO C. YOUNG, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO IN 0., OFNEW YORK, N. Y., A CORPORATION WIRED RADIO, OF DELAWARE.

RADIO TELEGRAJPH KEYING SYSTEM.

Application filed December 15, 1926. Serial No. 155,026.

My invention relates broadly to high fre queney signaling circuits andmore particularly to a circuit arrangement for telegraphically keying anelectron tube transmitter.

One of the objects of my invention is to provide a circuit arrangementfor a high frequency crystal controlled transmitter wherein theoperation of an electron tube oscillator is arranged to be sustained bythe constant frequency oscillations of a iezo electric crystal elementboth during anii intermediate the signaling intervals, while the effectof the oscillations upon a power amplifier system may be interrupted forthe production of signals.

Another object of my invention is to provide an electron tubetransmitter including a piezo electric crystal controlled oscillator andpower amplifier system in which the operation of the power amplifiersystem is blocked for the making of signals, while the crystalcontrolled oscillator is maintained in continuous operation although atdifl'erent degrees of amplitude.

Another object of my invention is to provide a circuit arrangement for apiezo electric crystal controlled oscillator and power amplifier systemhaving connections interposed between the grid circuit of the poweramplifier system and the input circuit of the oscillator for subjectingthe power amplifier circuit to alternate conditions of blocking whilethe oscillator circuit is maintained in varying degrees of oscillationduring and intermediate the signal intervals.

y invention will be more clearly under stood from the specificationhereinafter following by reference to the accompanying drawings, inwhich: I

Figure 1 is an elemental circuit diagram illustrating the principle ofmy invention; and Fig. 2 illustrates a piezo electric crystal controlledoscillator system operating in conjunction with a power amplifier s stemand shows diagrammatically the arrangement of the keying circuit of myinvention.

Referring to the drawing in detail, reference character 1 designates anelectron tube having its circuits arranged for the generation of highfrequency oscillations. Reference character 2 designates a poweramplifier tube having circuits connected thereto upon which the highfrequency oscillations generated within the circuits of tube 1 areimpressed. The piezo electric crystal 3 is connected in series withcondenser 4 and ammeter 5 with the input circuit of tube 1. A choke coil6 is illustrated in shunt with the piezo electric crystal circuit andthe input circuit of tube 1. The output circuit of tube 1 is connectedwith the input circuit of tube represented by 11. eying circuit 12 isconnected in shunt with the resistance 10.

It will be noted that any current flowing from the plate supply source 8through resistance 10 will result in a voltage drop across it which isnegative at point A with respect to the potential 9 of the filaments. Asthe positive terminal of the generator 11 is connected to the filamentelectrodes through the same resistance 10 any potential developed alongresistance 10 will add to that of the source 11 thereby increasing thenegative potential applied to the grid of the amplifieritube 2. As thisresistance is in the common plate return and as the master os- 1 mustpass through current although reduced, gives enough additional negativebias pptential to block the grid of the amplifier. hen this resistanceis adjusted to the proper value, the master oscillator will continue tooscillate at reduced power and the amplifier tube will be blocked. key12 is closed the resistance 10 18 shorted out and the negative biasingtential 11 and filaments ae connected directly together in a normalworking position.

In Fig. 2 I have illustrated the application of my invention to a radiotransmission system in which the tubes 1 and 2 hold the same relation ofoscillator and amplifier with respect to each other. The cathodes of thetubes are heated from an alternating cur rent supply source by currentsupplied by transformer 14 made up of primary winding 15 and secondarywinding 17. The in put circuit of the oscillator tube 1 includes thepiezo electric crystal' 3, condenser 4 and ammeter 5 in shunt withchoke'coil 6 and battery 18. This arrangement provides for the operationof the piezo electric crystal 3 under conditions of no load. The outputcircuit 01'} the oscillator tube 1 is coupled to the input circuit ofthe power amplifier tube 2 through the put circuit of the poweramplifier tube 2 includes the tuned circuit 20, from which energy may betransferred to a succeeding stage of amplification or to a transmissioncircuit. The high potential source 8 supplies current to the platecircuits of both tubes 1 and 2. The generator 11 supplies a biasingvoltage to the grid circuit of the power amplifier tube 2. Theresistance 10 n the common lead between generators 8 and 11 isillustrated as shunted by a resistance 21 and capacity 22 and by key 12.The circuit 21-22 operates to prevent spark ing at the contacts ofthekey 12 or relay contact points that may be substituted for the key.

As the generator or source of potential 11 is required to supply onlythe working grid voltage of the amplifier 2, there is no loss inresistance in obtaining the required voltage. There is also no loss inplate power in producing the negative bias across a resistance in thecommon plate return. When the key 12 is open, the voltage'on the masteroscillator plate is reduced which results in the oscillator operating ata much reduced power intermediate the signaling periods. Thisarrangement tends to reduce local interference at receivers near thetransmitter and also tends to reduce considerably the power otherwiseneedlessly expended by the apparatus.

It will be understood that modifications in the circuit arrangement ofmy invention may be made without departing from the spirit of myinvention, and no limitations upon my invention are intended other thatare imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is as follows:

1. A high frequency signal transmission system comprising a. pluralityof electron tubes each having grid, filament and plate electrodes, inputand output circuits interconnecting said electrodes, including a circuitto interlink the output circuits of one of said tubes with the inputcircuit of a succeeding tube, the circuits of one of said tubes beingarranged to sustain high frequency oscillations at a selected frequency,and another of said tubes being arranged to amplify the oscillationsproduced by the first mentioned tube, a source of high potential forsupplying power to the output link circuit 19. The outcircuits of eachof said tubes, a source of potential for impressing a high negativecharge on the grid electrode of the last mentioned tube, anda resistancedevice connected between said sources of potential and a point common totheinput and output circuits of the first mentioned electron tube, andmeans for abruptly changing the condition of said resistance element forcontrolling the operation of the electron tubes in accordance withtelegraphic signals.

2. A high frequency system comprising a plurality of electron tubeseachhaving grid, filament and plate electrodes, input and outputcircuits interconnecting said electrodes, a piezo electric crystalelement connected in the input circuit of one of said electron tubes,connections between the output circuit of said electron tube and theinput circuit of a succeeding electron tube for impressing highfrequency oscillations corresponding to the frequency of the piezoelectric crystal element upon the circuits of the last mentionedelectron tube, a high potential source for supplying power to the outputcircuits of each of said electron tubes, a high potential source forimpresing a negative charge upon the grid electrode of the lastmentioned electron tube, a common connection between said sources, andmeans disposed between said common connection and'a point common to theinput and output circuits of. each of said electron tubes forcontrolling the condition of operation of each of said electron tubecircuits in accordance with telegraphic signals.

3. A high frequency signal transmission system comprising a plurality ofelectron tubes each having grid, filament and plate electrodes, inputand output circuits interconnecting said electrodes, a piezoelectriccrystal element connected in the input circuit of one of said electrontubes, connections between the output circuit of said electron tube andthe input circuit of a succeeding electron tube for impressing highfrequency oscillations corresponding to the frequency of said ,piezoelectric crystal element upon the circuits of said last mentionedelectron tube, a high potential source for supplying power to the outputcircuits of each of said electron tubes, a high potential source forimpressing a negative charge upon the grid electrode of said lastmentioned electron tube, a common connection between said sources, ahigh resistance element disposed between said common connection and apoint common to the input and output circuits of each of said electrontubes, and means connected in shunt with said resistance element forabruptly changing the value thereof for controlling the operation ofsaid electron tube circuits in accordance with telegraphic signals.

signal transmission 4.'A high frequency signal transmission tron tubeand the input circuit of a succeedmg electron tube for impressing onsaid last mentioned electron tube sustained oscillations corres ondingto the frequency of said piezo electric crystal element, a highpotential source for supplying power to the output circuits of each ofsaid electron tubes, a high potential source for impressing a negativechargeon the grid electrode of said last mentioned electron tube, acommon connection between said sources, a resistance element -interposedbetween said common connection and a point common to the input andoutput circuits of said first mentioned elec tron tube, a keying circuitconnected in shunt with said element being proportioned in such mannerthat when said keying circuit is opened oscillations from said piezoelectric crystal element are feebly sustained in the circuits of saidfirst mentioned operation of said last mentioned electron tube issubstantially blocked, the closing of said keying circuit operating toplace said first mentioned electron tube in a condition for stronglysustaining the oscillations of said piezo electric crystal element whilesaid second mentioned electron tube is placed in a condition forincreasing the amplitude of the oscillations thus sustained.

resistance element, said resistance electron tube while the 5. In apiezo electric crystal controlled transmission circuit the combinationof a plurality of electron tubes each having grid, filament and plateelectrodes, input and output circuits interconnecting said electrodes, apiezo electric crystal element connected in the input circuit of one 'ofsaid electron tubes, the output circuit of said electron tube beingcoupled with the input circuit of a succeeding electron tube forimpressing oscillations at the frequency of said piezo electric crystalelement upon said second mentioned electron tube, a high potentialsource for supplying ower to the output circuits of each of saidelectron tubes, a high potential source for normally impressing anegative potentialupon the grid of said second mentioned electron tube,a common connection between said sources, a resistance element dis osedbetween said common connection an the circuits of said first mentionedelectron tube, a keying circuit connected in shunt with said resistance,the closingof said keying circuit operating to place the circuits ofsaid first mentioned electron tube in a condition for sustaining theoscillations of said piezo electric crystal element, said resistancewhen effectively included in the circuits of said electron tubesoperating to block the operation of said second mentioned electron tubesand reducing the tendency of the circuits of said first mentionedelectron tubes to sustain the oscillations of said piezo electriccrystal element.

LEO C. YOUNG.

